Hot idea

GROTON -- The newspaper clipping taped to the wall of Hugh McLaughlin's basement laboratory extols the wonder of science. ''Why is science fun?" it asks. ''When you make a discovery you realize that at that moment in time you know something that nobody else in the world knows."

For McLaughlin, a chemical engineer whose invention is included in a new exhibit at the Museum of Science, that moment came in December of 2001. Curious about a consulting client's use of heat to decontaminate soil, he'd built a reactor from a 3-inch pipe and toaster heating elements. One day he randomly filled it with activated carbon -- absorbent flakes, similar to the charred scrapings atop burnt toast -- widely used to remove taste and odor from public water supplies and as filters in everything from gas masks to stove vents.

For a quarter-century he'd worked with activated carbon and knew it as a material that didn't change -- not when the acidity of its environment was altered, for instance, or when heated with steam. But now, heated with air in a makeshift oven, the activated carbon slowly oxidized into carbon dioxide and generated a small amount of heat.

''That's the 'aha,' " McLaughlin says. ''That represents potential."

Six thousand hours and $60,000 later, he obtained a patent in January for his related discovery that the heated activated carbon quickly oxidizes vapors and liquids that pass through it, which, he says, could be useful in processing industrial pollutants. He also has a patent pending for using the reactor to regenerate spent activated carbon. In the first application of this technology, a Louisiana plant has launched a pilot program converting used activated carbon, its spongelike capabilities saturated, to good-as-new material at relatively low, pizza-oven-like temperatures.

McLaughlin is the only New Englander among 25 semifinalists whose inventions are on display at the ''Modern Marvels Invent Now Challenge" exhibit that opened yesterday. The other inventions -- selected from more than 4,000 entries to a contest sponsored by the History Channel's ''Modern Marvels" show -- range from a computerized method of building a house in a day to an automatic candle snuffer. In a competition reminiscent of ABC's ''American Inventor," the ''Modern Marvel of 2006" will be announced May 24. The grand prize is $25,000.

McLaughlin's technology, which works at 500 degrees Fahrenheit, offers the promise of a lower-cost, more environmentally friendly means of regenerating activated carbon and processing pollutants than current energy-intensive methods at 1,800 degrees, says Mick Greenbank, a chemist at the Pittsburgh-based Calgon Carbon Corp. ''The current carbon reactivation processes and equipment date to World War II," Greenbank says. ''This is one of the first innovations since then."

McLaughlin, 53, is a tall, bespectacled man, his hair and beard graying, dressed one recent morning in jeans, sneakers, and an orange T-shirt he got for coaching his son's soccer team.

He's an Albany, N.Y., native who turned down MIT to attend Harvey Mudd, a small, science-oriented college in California. He later earned a doctorate in chemical engineering at Rensselaer Polytechnic Institute, where he met his wife, who was a fellow engineering student. She tells him that the description of his invention -- ''Activated Carbon Facilitated Oxidation," or AC FOX -- is harder to understand than the descriptions of his two dozen ''Modern Marvel" competitors.

Pressed to explain his work in layman's terms, McLaughlin vividly compares a speck of activated carbon to a bag of potato chips, whose nooks and crannies create a large interior surface area. But his first instinct is to use words like ''microporous."

Until -- or unless -- he earns money from AC FOX, McLaughlin earns a living by consulting and satisfies his curiosity by inventing. ''Consulting, you just get to tell them what you know," he says. ''I really like the thrill or working with technology myself."

His cluttered basement office, where a small refrigerator holds both apple cider and waste from the conversion of corn to ethanol, sits off the playroom of his two young sons. Across the playroom is a cluttered basement laboratory that smells of burnt wood from his wee hours conversion of sawdust to activated carbon in a small pot atop a camping stove. ''My wife and I have an understanding," he says. ''If I steal it from the kitchen, I have to buy her a new one."

When McLaughlin imagines the aroma of baking bread wafting from a commercial bakery, he thinks of the smog-contributing ethanol vapor also in the air and the possibility that his technology could process the pollutant.

He never got around to exploring the soil purification method that piqued his curiosity in the first place. ''This is a total tangent," he says. ''I stumbled on it one day. What right do I have to walk away?"